It is found that loosening of the acetabular cup in cemented total hip replacement often happens about 5-10 years after operation. As more and more prostheses have been mounted into yound and bone deficient hips nowadays, revision cases for replacing the loosened acetabular cup have become significant part of daily work of hip surgeons. Bone loss caused by loosened cup in cemented hip as well as uncemented hip, together with bone defect in dysplastic and protrusio hip are now the main concerns of surgeons.
In comparision with the femoral stem, much less attention has been paid to the fixation of acetabulum. Although the benign behavior of a radiologically loosened acetabular cup has given clinicians false impression in short term, the difficulties in reconstruction of bone deficiency and the poor results after massive bone graft at long run in loosened cup have alarmed surgeons to face the problems earlier on. At present the only way to manage massive bone loss is bone graft either by segmental bone or bone chips, maybe an autograft or allograft. Then, how to protect the bone graft may be the only way to get out of the mess.
Stemmed tibial tray in TKR has been proved of the capability to enhance the fixation of the tray from lossening either biomechanically or clinically. Based on the same principle and studies of the comparative anatomy of the pelvic bone, it is believed that the iliopubic bone bar similar to the diaphysis of long bones is the best part for the fixation of a stemmed prosthesis for the pelvis.
Therefore, it is an object of the present invention to provide an improved acetabular cup assembly which may obviate and mitigate the above-mentioned drawbacks.